In the processing of high mercury crudes, accumulation of elemental mercury may occur in the overhead sections of distillation columns of refineries, requiring special equipment handling and maintenance. Additionally, some of the mercury may accumulate in scale in the upper sections of the columns and remain in undesirable amounts in the light products such fuel gas, LPG, and light naphthas. Mercury can be removed from these light products by use of adsorbents in commercially licensed mercury removal units (MRUs). These MRUs need to be placed on several light product streams. Also, they have a limit in the amount of mercury which they can remove. If the mercury content of the light products increases to a higher value than the MRU can handle, mercury can pass through the unit. Further, MRUs are designed to remove elemental mercury by a chemical reaction with the adsorbent. If the mercury is in a particulate form of fine HgS, this is not particularly reactive with the adsorbent and mercury can pass through the unit.
As the mercury content of crude increases, there is an interest and need for improved methods and systems to control/reduce mercury levels in crudes, and preferably in the overhead sections of a crude distillation column.